Layout destroyed in classic editor

After investigating the cause, I found that WordPress 7.0 changed the CSS for #major-publishing-actions from display: block to display: flex with justify-content: space-between. This causes all child elements (#duplicate-action, #rewrite-republish-action, #delete-action, #publishing-action) to be laid out horizontally in a single row.

The Duplicate Post plugin CSS still assumes the old block layout and does not account for this new flex container.

Steps to reproduce:

1. Install WordPress 7.0
2. Activate Duplicate Post plugin
3. Open any post in the Classic Editor
4. Observe the publish metabox — all links and buttons appear on one line

Workaround:
Adding the following CSS fixes the layout:

#major-publishing-actions {
    display: block !important;
}

Environment:

• WordPress 7.0
• Duplicate Post (latest version)
• Classic Editor plugin